Mud guard for core drills



Jan. 24, 1933. MACREADY 1,894,997

MUD GUARD FOR CORE D ILLs Original Filed March 14. 1929 INVENTOR Patented Jan. 24, 1933 UNITED STATES PATENT? OFFICE HUD GUARD FOR CORE DBILLS Application filed March 14, 1929, Serial No. 346,955. Renewed November 23, 1982.

My invention relates to a simple, new and improved apparatus for preventing chunks of mud, cavings or dbris from entering and obstructing the core receivin barrel of a core drill during the operation 0 lowering it into In the operation of core drilling t 1s usually necessary to lower the core drlll down the hole each time a core is desired. In core drilling"\ in some oil regions, such as Callfornia, formations are often soft and cavey holes may deviate from vertical, and mud laden fluid is used in the hole. In ordinary practice the lower end of the core receivingbarrel is open and is usually the. most advanced portion of the core drill. When a core drill is lowered into a hole it naturally slides along the lower side of the hole 1f the hole is not exactly vertical and pushes a plle of scrapings, cavings, dbris and mud chunks ahead of it. This dbris accumulates d rectly in front of the mouth of the core receiving barrel. If the core barrel is open or provided with a check valve communicating with the drill pipe above then a portion of the fluid entering the lowering drill pipe can enter it through the core barrel as well as through the conventionalcirculation ports. This condition creates an upward current 1n the core receiving barrel which carries chunks of dbris up into the core receiving barrel. The larger chunks may not be able to pass the openin at the upper end of the barrel and are trappe to block the barrel.

In extreme cases the upper end of the core receiving barrel may become so tightly plugged that the fluid pushed ahead of the incoming core has no exitwith the result that the core is prevented from entering the barrel and recovery reduced. Even when core recovery is not reduced the presence of dbris in the core receiving barrel is undesirable because of contamination of the core.

From the fore oing remarks it willbe readil understood that a means of preventing dbris accumulating in the core receiving barrel will be very useful.

An object of my invention is to provide :1.

closure which will partially close the lower end of the core .receivin barrel during lowering into a hole sufliciently to exclude chunks of dbris but be open enough to allow liquid to. enter the barrel to relieve pressures and also to provide means on the closure to permit ready installation and permit its removal from the entrance of the core receiving barrel when coring is commenced.

With the foregoing and other objects in view which will be made manifest in the fol- 1 lowing detailed description and especially pointed out in the appended claims, reference is had to the accompanying drawing for illustrative embodiment of the invention, wherem:

Figure 1 is an elevation showing it installed in the receiving barrel, shown in section;

Fi ure 2 is another elevation of my invention ut viewed from a direction at right an les to the last;

igure 3 is a cross section of my invention at the mark 3-3, viewed looking down; and,

Figure 4 is an elevation of a modified form of m invention for use in core barrels provide with barbed retaining means and is shown in installed position, the core barrel being partially shown in section.

Similarnumerals refer to similar parts 89 throughout the several views.

In the accompanying drawing the body of the mud guard, designated as 1, is a piece approximately five diameters in length, preferably of hard wood although other ma- 35 terials can be used. The lower end of the piece 1 is preferably provided with a blunt conical point 2 suitable to deflect chunks of dbris aside. Slightly above the lower end 2 is an upwardly facing projection 3 ex- 90 tending out beyond the lower end 9 of the core receiving barrel 10. This projection can be made in the form of a transverse piece of wood or other material 7 insertedthrou h a hole in body 1, or it may be turned on t e bod as a one-piece construction such as the ro ection 3a on body lain the modified orm shown on Figure 4. Above the rojection 3 I provide sprm c5 of my invention mouth of a core the latter being partially barbs such as: arbs 4 which may be attach to the body 1 by tacks 5 or other suitable means as shown in Figure 1, or such as barbs 40 attached to the core retaining device 8a of core drill 10a as illustrated in Figure 4. The barbs can best be made of strips of thin sheet metal, 20 gauge galvanized sheet iron being found very satisfactory.

(lo-operating with the barbs is an convenient shoulder as shoulder 6 on t e interior wall of the core retainer 8 of core barrel 10 co-operating with barbs 4, or as shoulder 6a on body 1a co-operating with barbs 4a of the core retainer 8a. The form shown in Figure 1 has a shoulder 6b so that it can be used on either form of core retainer. The shoulder 6a or 66 can be turned directly on body 1 or 1a or it can be formed by a metal collar attached to the body. The purpose of the co-operating barbs and shoulder is to prevent the mudguard falling out of the core drill during lowering into the hole, and to permit free upward movement of the mud guard in the core barrel ahead of the incoming core. The mud guard should be pzeferably made to have a specific gravity of tween 1.500 and 2.000 (referred to water= 1.000) so that it will not be so light as to float to the top of the core barrel ahead of the core or on the other hand be so heavy as to crush the core. This is easily accomplished by selection of materials.

The form shown in Figure 1 can be used in core drills having either barbed or shoulder retaining devices. The form shown in Figure 4 is for use in core drills provided with barbed retainers. For use in core drills having shouldered retainers the shoulder 66 can be dispensed with.

The installation of my invention is very simple. I first inspect the barbs to see that they s read sufliciently to engage the shoulder. next insert the upper end of the body in the mouth of the core receiving barrel and apply ressure, say of my hand, to the lower pomte end and push the mud guard into the arrel until the projection 3 touches the lower end 9 of the core drill. The mud guard is thus installed and the barbs engage the shoulder to prevent it falling out.

The underground operation is also very sim le. As soon as the core drill enters the liquid standing in the hole the liquid can enter to fill the core barrel through space 11 between the mud guard and the core receivin barrel but this space is too narrow to adm1t large chunks of dbris which are deflected aside by the pointed end of the mud guard. The core drill is lowered until point 2 touches the bottom of the hole and then the weight of the core drill etc. comes on the projection 3 shearing or breaking it ofi and forcing the mud guard into the core receiving barrel. Goring then proceeds with the mudguard resting li htly on the top of the core. When the core drill is brought to the surface with invention as defined by t e appended claims. I

I claim as my invention: 1. A mud guard for core drills comprismg a body provided with a lateral projection thereon, a shoulder on said body facin said pro'ection, and resilient barbs attached to said ody between said projection and said shoulder projecting from said body and pointing in the direction of said projection. 2. A mud guard for a core drill comprismg a wooden stick and resilient metal strips each attached at one end to said stick and having their freeends normally urged away from said stick to a width greater than the bore of said drill but yieldable to contract to a width less than the bore of said drill.

In testimony whereof I have signed my name to this specification.

GEORGE A. MACREADY. 

